Circuit breaker with controlled instant of operation



H. GREBER Dec. 26, 1967 CIRCUIT BREAKER WITH CONTROLLED INSTANT OF OPERATION Filed Sept. 7, 1965 FIG.|

INVENTOR. 74? W United States Patent 3,360,684 CIRCUIT BREAKER WITH CONTROLLED INSTANT OF OPERATION Henry Greber, 225 W. 80th St., Apt. 8-D, New York, N.Y. 10024 Filed Sept. 7, 1965, Ser. No. 485,462 4 Claims. (Cl. 317-11) ABSTRACT OF THE DISCLOSURE This invention is related to an AC circuit breaker of high current interrupting capacity, for any practical voltage level, which is provided with a control device arrangement that trips the breaker at a time when the curve of the current passing through the breaker, or the voltage on its line side go through zero. The tripping as well as the closing circuits of the breaker are provided each with a relay controlled by two electronic tubes. One of them has a grid provided with a hole through which the electron beam electrostatically deviated closes the cathode-anode circuit given that the triode connected in series with this tube is in a conductive state, both conduct simultaneously when the current wave, or voltage wave passes through a predetermined point. If the mechanical delay of the breaker is added to the time corresponding to this point the time will be received at which the current, or the voltage wave respectively goes through zero.

The purpose of this invention is to provide a circuit breaker of great current interrupting capacity for any alternating voltage, including the high and extra high voltage levels, and yet inexpensive, and therefore capable of replacing the much more expensive oil, air blast, sulfurhexafluoride and vacuum breakers. The method used to achieve these objectives consists in opening the circuit breaker precisely at the moment when the voltage curve goes through zero, and close it exactly at the moment when the voltage reaches its maximal value. A modification of this method resides in opening the circuit breaker when the current through it passes through its zero value. In application if this method, and electron tube with plates capable of deviating the stream, and a simple triode vacuum tube, both in connection with a potential transformer on the line side of the breaker are used. These devices are introduced into the circuit of the relay triggering the tripping coil of the circuit breaker. Similar devices are introduced into the circuit of the relay operating the closing coil of the breaker. The function of these devices is to delay the action of the tripping signal coming from the line relay, until the voltage curve passes through the predetermined point. The line relay can be either a simple overcurrent, or a directional, or a distance, or any other kind of relay. When the predetermined point on the voltage curve is reached, the tripping or closing coil is set in operation. The time necessary by the breaker mechanism to open or close the breaker must be oscillographically determined, so that it is precisely known. In I order that the tripping and closing times be independent from the momentary value of the auxiliary voltage used for operation of the coils, if they were fed from an alternating current source, both the tripping and closing coils are operated with direct current.

The nature of this invention and its further advantages will become apparent from the following specification in connection with the accompanying drawing.

In this drawing, FIGURE 1 illustrates the voltage curve in which the tripping time of the breaker, shown to be a little less than two cycles, is indicated. In FIGURE 2 can be seen a single-line, schematic control connection diagram of the breaker. This diagram shows only one pole of the breaker. It is to be understood that other poles of the circuit breaker are likewise connected. The one pole breaker is designated with the numeral 1. On the line side 2 of this breaker is connected potential transformer 3, whose secondary winding is linked to relay R1. Relay R1 gets its tripping signal through cable 4, which connects this relay to the line relay, which is not shown in this diagram, since it is not a part of the circuit breaker. Relay R1 is also connected to the pushbutton PBl, serving for manual tripping of the circuit breaker. When relay R1 is energized through the action of the tripping signal, the voltage on the secondary winding of the potential transformer is conducted both, to the deviating electrostatic plate 5 of the electron tube 6, and also to grid 7 of electron tube 8, through the intermediary of capacitor 9, and resistor 10. If grid 7 is on the predetermined potential, there is a conductive path between cathode 11 and anode 12 of the triode. For the same value of the potential on the secondary side of the potential transformer 3, the electron beam 13 between cathode 14 and anode 15 of electron tube 6, passes through the tiny hole 16 made in screen 17. Then a conductive path between cathode 14 and anode 15 exists. When the conductive paths between cathode 11 and anode 12, and between cathode 14 and anode 1S exist at the same time, relay R2 is energized. Relay R2 energizes then, in its turn, the tripping coil TR, which trips the circuit breaker. The heating circuits for cathode 11 of triode 8, and for cathode 14 of electron tube 6 are not shown. Also the source of voltage for the circuits between said cathodes and anodes are not shown. These omissions are made for the sake of clarity, in order not to obscure unnecessarily the diagram. The control for closing the circuit breaker is similar to that for its tripping. When relay R3 receives, through cable 18, its closing signal from the line relay, which is not shown, or from the pushbutton P32, serving for manual closing of the breaker, it closes a pair of its contacts. Through these contacts, relay R3 conducts the voltage from the secondary winding of the potential transformer 3 to the electrostatically deviating plate 19 of electronic tube 20, and through capacitor 21 and resistor 22 this voltage is also conducted to grid 23 of electron tube 24. When the voltages on the deviating plate 19, and on the grid 23 corresponds to the predetermined point on the voltage curve, the conductive path between cathode 25 and anode 26 is established, as well as the conductive path between cathode 27 and anode 28. In this case the electron beam 31 of tube 20 passes through the small hole 29, made in screen 30. If the two conductive paths exist simultaneously, relay R4 is energized and triggers the closing coil CL. Coil CL closes the circuit breaker. Also the heating circuits of cathodes 25 and 27, and the sources of the direct current voltages for the cathode-anode circuits are omitted for clarity of the diagram.

As mentioned, this circuit breaker can be alternatively set to open when the current flowing through it passes through its zero value. For this purpose, the current transformer 32 shown in dotted lines, is connected to relay R1, which in this case is disconnected from the potential transformer 3. But, the potential transformer is still necessary for operation of relay R3, for closing the breaker at peak value of the voltage on its line side.

In operation of this device, if it is desired to trip the breaker at point 0 on the voltage curve shown in FIG- URE 1, and if the time required by the breaker mechanism for tripping is equal to the segment AO on the abscissae axis, then the tripping has to be started at point A. To point A corresponds voltage V The deviating plate has to be adjusted so that when the voltage on it will be V the electron beam from cathode will pass exactly through the hole 16 in screen 17, and reach anode 15. However, as can be seen in FIGURE 1, to voltage V correspond two points A and B. The control arrangement of the breaker has to discriminate between these two points. This discrimination is accomplished by means of capacitor 9 and resistor 10 in conjunction with the triode 8. Capacitor 9 is connected in parallel to the secondary winding of the potential transformer 3. Resistor 10 is hooked up in series with capacitor 9. The current through capacitor 9 will be leading in respect to the voltage on the secondary side of potential transformer 3, and so will the voltage drop on resistor it since this resistor, as stated, is connected in series with capacitor 9. The voltage drop is represented as sinusoid C in FIGURE 1. It can be seen that this voltage drop is of opposite polarity for point A than it is for point B, and this fact is utilized for discrimination between the two points. The voltage drop on resistor 10 appears as the difference of potentials between cathode 11 and grid 7 of the triode 8. If the potential of the grid 7 is positive in respect to that of cathode 11, the circuit between cathode 11 and anode 12 is closed, and triode 8 conducts. This state corresponds to point A on the voltage curve. For point B the triode does not conduct, since its grid '7 is on negative potential in respect to its cathode 11. Hence, the breaker can be tripped only in point A, not in point B. A tripping operation started at point A will end in point 0, at which the value of the voltage is zero. The same reasoning can be repeated in case when it is desired to trip the breaker at the moment when the current flowing through it passes through zero. The voltage on the secondary side of the current transformer will then completely substitute the voltage on the secondary side of the potential transformer. It is worth mentioning that capacitors 9 and 21 can be replaced with inductances.

For the closing operation of the breaker, point B is the desired point of commencement of the motion of the closing mechanism, since the breaker has to close at a time when the voltage on its line side reaches its peak. In FIGURE 1 this point is designated with the letter D. In this example, it is assumed that the time necessary for closing the breaker is exactly equal to the time necessary for its tripping. It is only a matter of setting of the control of the breaker, if these times are diiferent. When relay R3 gets its closing signal through cable 18 connecting relay R3 with the line relay, not shown in this diagram, it closes a pair of its contacts. The same contacts will be 'closed it relay R3 would get its closing signal from pushbutton PB2, serving for manual closing of the breaker. In both cases the secondary voltage of the potential transformer 3 will be conducted to the deviating plate 19 of electronic tube 20, and the voltage drop on resistor 22 will appear between cathode 25 and grid 23 of triode 24. It can be seen that the connections from resistor 22 to triode 24 are reversed in comparison to the connections between resistor 10 and triode 8. This is due to the fact that the voltage drop curve C in FIGURE 1, shows a negative value at the point B. When the point on the voltage curve corresponding to point B on the abscissae axis is reached, grid 23 is under the voltage V At the same time deviating plate 19 is under the voltage V Electron tube is adjusted so that when its deviating plate 19 is under the voltage V electron beam 31 from cathode 27 passes through the minute hole 29 in screen 30, and

reaches anode 28. Thus electron tube 20 becomes conducting, as far as its cathode-anode circuit is concerned. At the same time, also in triode 24 the circuit between cathode and anode 26 is closed. Consequently, relay R4 is energized, and energizes in its turn the closing coil CL, which closes breaker 1.

Through the proper timing of the current interruption process, either at voltage or at current passage through zero, the current interruption itself is substantially facilitated. Another, not less important advantage of this breaker is that the voltage surge caused by it at its closing or opening of the circuit is minimal. Because of these advantages, this circuit breaker designed as an air circuit breaker can be applied at points at which at present oil, sulfurhexafiuoride, air blast or vacuum breakers are used. While the operation of this circuit breaker has been described under the condition of using electronic tubes for its control, it is obvious that this control can be easily transistorized. There is no problem in substituting transistors for the described triodes, and using Hall devices for the mentioned electron tubes with deviating plates. The triodes and the electron tubes with electrostatic plates can easily be substituted also by other electronic devices commercially available today. While the use of this control arrangement has been described in combination with a circuit breaker, it is to be understood that it can also be used in conjunction with disconnect switches, mercury switches, and other switching devices used for closing and opening of circuits.

What has been described and illustrated is what is regarded to be the most typical embodiment of this invention. It is to be understood that this is merely an example, and that many modifications, variations, re-arrangements and changes by addition, omission, and substitution can be made, Without departure from the spirit of this invention and its scope as defined by the following claims.

What is claimed as new in the art is:

1. A circuit breaker with controlled instant of operation whose tripping and closing coils, each are triggered by a separate relay, each relay being energized through the intermediary of the cathode-anode circuits of at least two electron tubes, one having a grid means which make the cathode-anode path of said tube conductive when said grid is impressed with a predetermined value of a voltage drop on a resistor in series with reactance means fed from the secondary winding of a potential transformer connected to the line side of said circuit breaker, the second of said tubes having at least one plate electrostatically deviating the electron beam between the cathode and anode of said electron tube, which has a screen provided with a small hole through which said electron beam of said second electron tube passes when the voltage on said deviating plate reaches a value predetermined from the voltage curve so that, if the time corresponding to said predetermined voltage value is added to the time necessary for the breaker mechanism to perform a switching operation, the sum of the two times correspond to a point at which the voltage on the line side of said breaker is zero, and said voltage drop on said resistor connected in series with said reactance means serves to discriminate between a voltage value on the rising or the declining part of the voltage sine wave.

2. A circuit breaker, as in claim 1, having a closing coil triggered by a relay, which is energized through the intermediary of two cathode-anode paths of at least two electronic tubes connected in series, the rfirst of which has a grid connected to a resistor in series with reactance means fed from a potential transformer connected to the line side of said breaker, the second electron tube has at least one plate electrostatically deviating the electron beam from the cathode to the anode of said second electron tube, said grid of said first electron tube adjusted so, by means of a bias voltage source, that the cathodeanode circuit of said first tube is closed when the voltage drop on said resistor reaches a value corresponding to the peak value of the voltage on the line side of the breaker, and said plate of said second electron tube adjusted so, by means of a source of a bias voltage, that said electron beam of said second tube passes through the hole of the screen of said second tube When the voltage on the line side of said breaker goes through a value determined from the voltage sine wave, With the time corresponding to said value added to the time necessary for the tripping mechanism to trip the breaker will result in a point to which the corresponding voltage is the peak value of the voltage sine Wave.

3. A circuit breaker as in claim 1, with said electronic tubes replaced with transistors and Hall devices.

4. A circuit breaker as in claim 1, With a current transformer connected to said electronic means for the breaker control.

References Cited UNITED STATES PATENTS Rolf et a1 3l7--11 X Perolini 31711 X Berkery et al. 307-133 X Baude 317-11 =Perry et a1. 317-11 Chia Huan Lee 317-11 MILTON o. HIRSHFIELD, Primary Examiner.

J. D. TRAMMELL, Assistant Examiner. 

1. A CIRCUIT BREAKER WITH CONTROLLED INSTANT OF OPERATION WHOSE TRIPPING AND CLOSING COILS, EACH ARE TRIGGERED BY A SEPARATE RELAY, EACH RELAY BEING ENERGIZED THROUGH THE INTERMEDIARY OF THE CATHODE-ANODE CIRCUITS OF AT LEAST TWO ELECTRON TUBES, ONE HAVING A GRID MEANS WHICH MAKE THE CATHODE-ANODE PATH OF SAID TUBE CONDUCTIVE WHEN SAID GRID IS IMPRESSED WITH A PREDETERMINED VALUE OF A VOLTAGE DROP ON A RESISTOR IN SERIES WITH REACTANCE MEANS FED FROM THE SECONDARY WINDING OF A POTENTIAL TRANSFORMER CONNECTED TO THE LINE SIDE OF SAID CIRCUIT BREAKER, THE SECOND OF SAID TUBES HAVING AT LEAST ONE PLATE ELECTROSTATICALLY DEVIATING THE ELECTRON BEAM BETWEEN THE CATHODE AND ANODE OF SAID ELECTRON TUBE, WHICH HAS A SCREEN PROVIDED WITH A SMALL HOLE THROUGH WHICH SAID ELECTRON BEAM OF SAID SECOND ELECTRON TUBE PASSES WHEN THE VOLTAGE ON SAID DEVIATING PLATE REACHES A VALUE PREDETERMINED FROM THE VOLTAGE CURVE SO THAT, IF THE TIME CORRESPONDING TO SAID PREDETERMINED VOLTAGE VALUE IS ADDED TO THE TIME NECESSARY FOR THE BREAKER MECHANISM TO PERFORM A SWITCHING OPERATING, THE SUM OF THE TWO TIMES CORRESPOND TO A POINT AT WHICH THE VOLTAGE ON THE LINE TIMES CORRESPOND TO A IS ZERO, AND SAID VOLTAGE DROP ON SAID RESISTOR CONNECTED IN SERIES WITH SAID REACTANCE MEANS SERVES TO DISCRIMINATE BETWEEN A VOLTAGE VALUE ON THE RISING OR THE DECLINING PART OF THE VOLTAGE SINE WAVE. 